Sneer at old-school BlackBerry smartphones if you must, but I still miss their push-button keyboards. They let you pound out text messages with firm, decisive keystrokes that no touchscreen phone can equal. Too bad you can’t temporarily replace an iPhone’s touchscreen with real push buttons when you need to type something.

Oh, wait. You can. SoloMatrix Inc., a company in Washington state, has come up with a remarkable solution­ — a fold-away keyboard that fits over the virtual keyboard on an iPhone screen. The Spike 1 fits around the phone like an external case. Its keyboard is mounted on a hinge that lets the user fold it around onto the back of the phone when it isn’t needed. Now you can use the touchscreen as Apple intended. But when it’s time to type, you just flip the keyboard onto the front of the iPhone and start pecking away. The Spike 1 doesn’t require batteries, and it doesn’t tap the iPhone’s power supply. It simply uses physical buttons to press the virtual keyboard buttons on the phone’s touchscreen.

This hefty wristwatch contains a GPS receiver, to pinpoint your location. But it’s got other navigational niceties, like a compass for tracking your direction of movement, a speedometer, and an altimeter, in case you decide to jog up Mount Washington. Of course, there’s a clock too, with a stopwatch function in case you feel like timing yourself.

In addition, you get a heart rate monitor that straps onto your chest and beams radio signals to the watch. Now you get constant monitoring of your heart rate. All the data are recorded in the watch’s memory. Plug it into your home computer via a USB cable, and you can load that data into a fitness tracking program that’s included with the watch. Now you’ve got a permanent record of your progress.

On the downside, the Pyle watch is clunky, ugly, and uncomfortable. But as a sophisticated fitness tracker, it gets the job done.

Fans of the classic TV series “The Wire” know that “burner” was the show’s nickname for a cheap, disposable cellphone used by criminals to cover their tracks. Well, here’s an impressive app to let law-abiding types do the same thing, and without having to throw away an expensive iPhone afterward.

Burner is an online service that lets you purchase a temporary phone number to use in place of the one assigned to your phone.

Dial calls through the Burner app, and the person on the other end will see this temporary number.

If he calls you back, the call is routed to your iPhone’s real number. But your caller ID will display the Burner number, so you know the call is from somebody you may not entirely trust.

The app includes a number good for 20 minutes of talk and 20 text messages. Once activated, this number automatically expires after seven days. You can purchase credits that let you keep using the Burner number and provide extra voice minutes and text messages.

But the true beauty of Burner is the ability to discard a number. Use a Burner number for those unpleasant chats with bill collectors or former boyfriends. To prevent them from calling back, just hit the “burn” button, and the number no longer works.

There are lots of other temporary phone-number services out there, but Burner is unusually simple and attractive, especially for those of us who loved watching “The Wire.”

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